despite the mind-boggling mass of every maple, elephant, cricket, worm, mackerel, dandelion, and sparrow on Earth right now, there used to be a lot more. Poaching, deforestation, and other forms of human activity have dramatically reduced the mass of life on Earth. The mass of land mammals, for example, is one-seventh what it was before modern humans walked out of the African savannah.
4) Frogs are croaking from a nasty fungus
Frogs are often
sentinel species that scientists study closely because they are especially sensitive to changes in their environment, like temperature, rainfall, habitat loss, and invasive species. Sentinel species also serve critical roles as predators and prey in their habitats. Their fates are harbingers of broader shifts in the environment and they are often the first to show signs that changes are afoot.
Which is why scientists were so alarmed by the spread of a deadly amphibian fungus,
Batrachochytrium dendrobatidis, also known as the amphibian chytrid fungus or Bd. Scientists previously reported that this single pathogen has led to the decline or extinction of 200 frog species. But a new
study out in March showed that the die off has been even worse than they realized.
A Corroboree Frog walks across the gloved palm of reptile keeper. Only about 200 Corroboree frogs exist in the wild in their natural habitat of the Kosciuszko National Park in New South Wales. The frogs are threatened by the amphibian chytrid fungus.
Ian Waldie/Getty Images
Researchers reported that Bd has driven 90 frog species to extinction and forced another 124 to decline in numbers by more than 90 percent. This population crash has only been going on for about the last 50 years.
While the fungus is deadly on its own, humans have aided its spread around the world. The disease is hard to eradicate, but there is some evidence that the pace of decline is slowing down.
5) Life is disappearing, appearing, and evolving right in front of us
The
World Wildlife Fund reported that vertebrate populations have declined by a jaw-dropping average of 60 percent since 1970. That includes birds, mammals, fish, reptiles, and amphibians.
Yet even as species disappear, we do occasionally discover new ones. Scientists found five new frog species in
Madagascar, for example. It’s a regular reminder that we still don’t fully grasp all the nuances of life on earth, even as we unwittingly extinguish it.
One of the new frog species discovered in Madagascar.
PLOS One
But perhaps even more intriguing (and disturbing) is that we are changing life too. Researchers reported this year that as climate change raises average temperatures,
sea turtles are experiencing a dramatic change in their sex ratios. Temperature is a major variable in determining the sex of a reptile, and in one species, scientists found that female baby sea turtles now outnumbered males 116-to-1. It’s a development that could herald a population crash among turtles.
6) We have just over a decade left before the best-case scenario for global warming passes us by
The
Intergovernmental Panel on Climate Change, a group of the world’s top scientists convened by the United Nations, put out a stark report last year highlighting how little time we have left to limit global warming to 1.5 degrees Celsius, the most ambitious goal under the 2015 Paris climate agreement.
The key finding is that if we want to hit this target, we have to cut global greenhouse gas emissions in half compared to where they are now by 2030. By 2050, we would have to reach net zero emissions, and after that, we would even have to start withdrawing carbon dioxide from the atmosphere.
Otherwise, the window to 1.5 degrees Celsius closes, and we lock ourselves into more warming, which will lead to more sea level rise, more devastating extreme weather, mass migrations, and expensive declines in the global economy.
Workers uses farm machinery to navigate floodwaters from the Waccamaw River caused by Hurricane Florence in Bucksport, South Carolina.
Sean Rayford/Getty Images
Despite these findings, we’re far off track and only getting farther. Global
carbon dioxide emissions hit an all-time high in 2018. Atmospheric carbon dioxide levels crossed a record
411 parts per million, the highest levels since humans have existed. In the United States,
energy use hit a record high and greenhouse gas emissions started to rise again in 2018 after years of decline.
That said, we do know what we need to do to
accelerate progress in fighting climate change, from pricing carbon dioxide to eating less meat to supporting public officials who will advance critical policies. The IPCC report also provided goal posts of the
Green New Deal, a far-reaching proposal for the United States to take the lead in fighting climate change.
7) A coming verdict on our right to a safe climate
A wave of lawsuits hinging on damages wrought by climate change gained momentum over the past year. Interestingly, climate science isn’t what’s up for debate in these
climate lawsuits.
Rather, the key fights are over the legal rights to a safe climate and whether parties are owed damages from those that contributed to the problem.
In one set of cases, children and young people are suing the federal government for profiting off leases to fossil fuel extractors on public lands despite knowing the damages caused by rising average temperatures.
Earth Guardians Youth Director Xiuhtezcatl Martinez, one of the plaintiffs in the Juliana v. US climate lawsuit, speaks outside the US Supreme Court in 2017.
Robin Loznak/Our Children’s Trust
In another set of lawsuits, cities, states, and local governments are suing oil companies for posing a public nuisance. The argument is that fossil fuels produce heat-trapping gases, which in turn cause problems like sea level rise that threaten valuable shorelines.
At stake are billions of dollars in liability for some of the largest and most powerful institutions in the world. And the cases could set precedents that stand for generations. These lawsuits are now working their way through courts, in the United States and in other parts of the world. The outcomes of these cases are critical, but uncertain.
7 things we’ve learned about Earth since the last Earth Day